Integrated radio-frequency/wireless coil design for simultaneous MR image acquisition and wireless communication

Abstract

Purpose: An innovative radio-frequency (RF) coil design that allows RF currents both at the Larmor frequency and in a wireless communication band to flow on the same coil is proposed to enable simultaneous MRI signal reception and wireless data transfer, thereby minimizing the number of wired connections in the scanner without requiring any modifications or additional hardware within the scanner bore.

Methods: As a first application, the proposed integrated RF/wireless coil design was further combined with an integrated RF/shim coil design to perform not only MR image acquisition and wireless data transfer, but also localized B₀ shimming with a single coil. Proof-of-concept phantom experiments were conducted with such a coil to demonstrate its ability to simultaneously perform these three functions, while maintaining the RF performance, wireless data integrity, and B₀ shimming performance.

Results: Performing wirelessly controlled shimming of localized B₀ inhomogeneities with the coil substantially reduced the B₀ root-mean-square error (>70%) and geometric distortions in echo-planar images without degrading the image quality, signal-to-noise ratio (<1.7%), or wireless data throughput (maximum variance = 0.04 Mbps) of the coil.

Conclusions: The RF/wireless coil design can provide a solution for wireless data transfer that can be easily integrated into existing MRI scanners for a variety of applications.

Keywords: B0 shimming; RF coil; WiFi; Wireless; iPRES.

Figure 1:

The wired connections within a traditional MRI scanner (a) can be removed by transmitting MRI data (red line), shim control data (blue line), and peripheral systems data (magenta lines) wirelessly with an RF/wireless coil (orange) (b).

Figure 2:

A standard RF coil (a) was modified to further enable localized B₀ shimming(b), wireless data transfer (c), or both (d, e) by allowing an RF current at the Larmor frequency (red) for MR imaging, an RF current in a wireless communication band (orange) for wireless data transfer, and/or a DC current (blue) for shimming to flow on the coil. In this work, the MRI signal was transferred from the coil to the scanner through a conventional wired connection.

Figure 3:

SNR maps of the coil (red line) in the: (a) RF coil, (b) iPRES coil, (c) RF/wireless coil, and (d) iPRES-W coil configurations, showing that the SNR was not affected by the modifications made to enable B₀ shimming or wireless data transfer.

Figure. 4:

Localized B₀ inhomogeneities were introduced into a uniform phantom (b) with an RF-isolated perturbation loop (magenta line), resulting in severe geometric distortions in the corresponding EPI image (g). The iPRES-W coil (red line) was able to generate a magnetic field for shimming (c) that substantially reduced the B₀ inhomogeneities by more than 70% and the geometric distortions in the EPI images, without (d,i) and with (e,j) simultaneous wireless data transfer.

Figure. 5:

The images and SNR maps of the phantom acquired with the GRE (a,b), GRE-EPI (c,d), and SE-EPI (e,f) pulse sequences showed no degradation in either image quality or SNR during wireless data transfer between the iPRES-W coil and the AP at the 3.7, 9.7, and 15.7 Mbps data rates.